Outline

Objective

The OHTS (Ocular Hypertension Treatment Study) has shown that approximately 20% of patients diagnosed with ocular hypertension (OHT) and normal white/white (w/w)- visual fields do already have scotomas in short wavelength automated perimety (SWAP, blue/yellow perimetry). HRT-imaging is broadly used in the classification of early glaucomatous changes of the optic nerve head.

Methods

46 eyes of 23 consecutive patients with OHT were included into this study. They all had normal w/w-visual fields and underwent SWAP and HRT-topography of the optic nerve head. Visual field testing was carried out using the standard 30/2 test of the Humphrey-Field-Analyzer 750i. Topographic imaging of the optic disc was done with the Heidelberg Retina Tomograph (HRT). For stereometric analysis, the Heidelberg Engineering software version 1.11 was used.

Results

Mean patient age was 30 years. Mean maximum IOP was 26.3mmHg. Mean disc area was 2,13mm2 for the right, and 2,33mm2 for the left eye. The mean normalised cup-disc area ratio was 0.38 and 0.39, respectively. There were no scotomas on w/w-perimetry (MD=-1.85). Conspicious visual field testing by SWAP was noted for 28 eyes (61%), with a mean defect of -8.1dB. 28 out of the 46 eyes (61%) were classified as glaucoma by the Mikelberg discriminant function of the HRT-stereometric analysis, of which 20 eyes (71%) did also have noticeable SWAP defects. Thus, 44% of the included eyes were classified by both SWAP and HRT-topography as early glaucoma.

Conclusions

The significance of SWAP in detecting early visual field deficits in OHT patients is well known and emphasised by this study. The correlation of SWAP and HRT stereometric analysis of the optic nerve head underlines the value of HRT-topography for detecting early glaucomatous lesions in OHT patients. Further clinical trials are needed for validation, also including other prognostic parameters as e.g. corneal pachymetry.